Not a lot of people know that: The answers to the world's most baffling questions

Not a lot of people know that: The answers to the world's most baffling questions

EVER wondered what earwax is really for or whether the use of piped music increases sales? Now the answers to these and more baffling questions posed by readers of the New Scientist magazine are revealed in a brilliant new book.

Published: 10:15, Thu, December 13, 2012

Target: James Bond has dodged thousands of bullets

CEREAL CEMENT

Q My favourite breakfast cereals are Shreddies and Weetabix. The remnants in the bowl look similar but I can always tell which was which. A Shreddies bowl can be washed up quite easily while Weetabix clings like cement. Why the difference?

A Both Shreddies and Weetabix contain a high proportion of starch, which can form an adhesive paste with water. Starch consists of a mixture of amylose and amylopectin, polymers that can absorb water to form a gel. As the gel dries the water is expelled and bonds between the molecular chains reform, creating a semicrystalline "cement" which will adhere to any adjacent surface. This effect is much more noticeable with Weetabix than Shreddies because Weetabix is made of fine flakes of cereal compressed together while Shreddies are made from longer strands. That means Weetabix has a greater surface area of adhesive in contact with the bowl making it harder to clean.

SNAIL NAIL

Q Why do fingernails grow at least three times as fast as toenails?

A Toenails are subject to less wear and tear and so do not need to grow as quickly. According to Linden Edwards and Ralph Schott, who published a paper on the subject in 1937 in the Ohio Journal of Science, toenails grow at half the rate of fingernails. On average fingernails grow a little less that four centimetres a year. There is quite a big variation between individuals depending on heredity, gender, age and how much they exercise. Nails grow faster in the summer.

HOW WAX WORKS

Q What is earwax for?

A Earwax, also called cerumen, acts as a cleaning agent with lubricating and antibacterial properties. Cleaning occurs because the epithelium - the surface layer of skin inside the ear - migrates from eardrum to exit acting as a conveyor belt carrying dust or dirt out of the ear. At first this migration is as slow as fingernail growth but aided by jaw movement it accelerates once it reaches the entrance of the ear canal. When it gets to the final third of the ear canal, where cerumen is produced, the conveyor carries wax and whatever gunge it has accumulated towards the exit. Cerumen consists of a mixture of watery secretions from sweat glands and more viscous secretions from sebaceous glands. Some 60 per cent is keratin but it also contains dead skin cells, fatty acids, alcohol and cholesterol.

UP WITH THE LARK

Q Why do birds sing as dawn breaks? Indeed why do some sing at dusk? And for what reasons do they eventually stop?

A Birds sing more at dawn and dusk than at other times because that is when they can hear more birds singing. Frequently at these times the wind has dropped and a temperature inversion forms. This means a layer of warmer air forms above cooler air. This changes the way in which sound is carried through the air, refracting sound waves back towards the ground that otherwise would have dissipated in the air. The upshot is that sound is carried further at dawn and dusk. Thus if a bird devotes most of the energy it spends on singing to those times it is heard by the widest possible audience. Of course there are birds that can be heard singing at any time of day but even these will tend to sing more at dawn and dusk.

SAUCY DOGS

Q I have two female dogs whose urine kills the grass in patches all over the lawn. My mother advised feeding them tomato ketchup which I did and the patches stopped. Why does this work and should I really be feeding my dogs tomato ketchup?

A The urine acts as liquid fertiliser but can produce nitrogen overload where the puddle of urine is deepest. This "burns" the grass, creating a brown patch. Towards the outside of the puddle, where less nitrogen has been applied, there can be a fertilising effect leading to a ring of luxuriant, greener grass. The urine of dogs and bitches does not differ much but while dogs tend to deliver small samples of urine to mark their territory, bitches tend to empty their bladders, which ultimately can cause more harm. Urine is slightly acidic but so is tomato ketchup so it does not neutralise the urine as some people believe. Instead the salt content of tomato ketchup, juice or sauce makes dogs drink more, diluting the nitrogen in their urine. Be aware though that the increased salt intake can cause problems with existing kidney or heart conditions so cutting the protein content in your dog's diet is a better alternative and works just as well.

DIE ANOTHER DAY

Q James Bond must have had thousands of bullets aimed at him over the course of his movie career. He must be the most shot-at fictional film hero of all time. Can anybody calculate the odds of him not having taken a fatal hit after five decades?

A There is ambiguity over how many gunshots have been fired at Bond because in many gunfights it is not clear whom the shots are aimed at. However it is widely believed that over 22 films (not including the latest Skyfall) at least 4,662 shots have been fired at our hero. A static, well-aimed shot would almost certainly have proved lethal but assuming all 4,662 were "on the run" the real probability of any single shot proving fatal is about five per cent.Apart from gunshots there have been 130 attempts to kill him so he has very been lucky.

SOUND RETAIL

Q Is there any evidence that piped music in shops, pubs and similar establishments increases sales?

A Not only does it increase sales generally but tests have shown that music related to a product can do so directly. For example playing overtly French music in a supermarket will increase its sales of French wine or cheese. This is probably because the music creates a mental association with a product. It works with smells too. The piped smell of ground coffee or baking bread also increases sales.

TREE FELLERS

Q How many A4 sheets are in the average tree used for paper making?

A A 20-metre pine tree with a trunk 20 centimetres across would yield about 45,000 A4 sheets. This assumes that the density for wood is about 600 kilograms per cubic metre and that 50 per cent of the pulp is lost once the water and lignin are removed. It also assumes that the "density" of the required paper is 70 grams per square metre. An A4 sheet is 210 millimetres by 297 millimetres. Each sheet therefore has a mass of 4.4grams. However only about a third of the raw material for paper comes from virgin wood.Residue or leftovers - wood chips and scraps that would be dumped or incinerated to generate energy - make up another third. The final third is recycled paper.

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